1. Field of Invention
Exemplary aspects of the present invention relate to a method of forming electrodes, and more particularly to a method of forming electrodes that are used for electronic devices, such as semiconductor integrated circuit devices, optical devices and the like.
2. Description of Related Art
A lift-off method is used in the related art to form electrodes that are used in electronic devices, such as, for example, semiconductor integrated circuit devices, optical device and the like. For example, a lift-off method is often used in a process of forming electrodes of optical devices that use compound semiconductor. See, Japanese Laid-open Patent Application 2000-58481. A lift-off method is characterized in that minute metal film patterns can be formed by a simple technique, compared to a dry etching method.
A related art lift-off method is described with reference to FIG. 19A through FIG. 19F. First, a photoresist 912 having a predetermined pattern is formed on a substrate to be processed (base member) 10 (see FIG. 19A); an electrode material is then deposited on the base member 10 and the photoresist 912 by vapor deposition or the like to thereby form a conductive layer 20a (see FIG. 19B). Then the photoresist 912 is dissolved in a liquid 25, such as a stripping liquid, acetone or the like (see FIG. 19C). By this, the photoresist 912 is removed from the base member 10 (see FIG. 19D or FIG. 19E). In this instance, there may be cases when a conductive layer 20x formed on the photoresist 912 may adhere to the base member 10. Accordingly, as indicated in FIG. 19D or FIG. 19E, the conductive layer 20x formed on the photoresist 912 is removed to obtain a conductive layer 20 having a predetermined pattern (see FIG. 19F). The conductive layer 20 has an opening section 22 at a location where the photoresist 912 was provided, as shown in FIG. 19F).
Methods to remove the conductive layer 20x include, for example, a method to blow off the conductive layer 20x by jetting liquid or gas 13 under a high pressure against the conductive layer 20x (see FIG. 19D), and a method to remove the conductive layer 20x from the base member 10 by adhering an adhesive tape 14 to the conductive layer 20x and peeling the adhesive tape 14 (see FIG. 19E).